macros.scm and rule-trans-set.scm
rule-trans-set.scm: known-rules-update is now really ugly! (but working)
will be replaced with topological sort
known-rules-update now loops until there are no
further changes in the rule-candidates-list (each
time). this should really make it work now.
makros.scm replaced with macros.scm
macros.scm: in make-is-out-of-date? there was no check for
file-existence of each prereq